1. Technical Field of the Invention
The present invention relates generally to digital communication systems. More particularly, and not by way of limitation, the invention is directed to an Ethernet Digital Subscriber Line Access Multiplexer (DSLAM) and method providing dynamic service selection and end-user configuration of service bindings.
2. Description of Related Art
Ethernet is a packet-based transmission protocol that is primarily used in local area networks (LANs). Ethernet is the common name for the IEEE 802.3 industry specification. Data is transmitted in Ethernet frames. Each frame includes a preamble with 64 bits utilized for synchronization. A Start of Frame Delimiter (SFD), a destination address, a source address, and a length/type identifier follow the preamble. Media Access Control (MAC) client data, together with a Packet Assembler/Disassembler (PAD) may vary in length from 46 to 1500 bytes (octets). A Frame Check Sequence (FCS) adds four more octets. The frame size is counted from the destination address to the FCS, inclusive, and thus may vary between 64 and 1518 octets, not including a Virtual Local Area Network (VLAN) tag, which adds 4 octets.
When establishing a data session between an end-user device and a service provider, a service binding creates a logical connection between the end-user device and a service provided by some form of service provider, for example, a Network Service Provider or Application Service Provider. Two types of service bindings currently in use in the industry are referred to herein as the basic service binding and the advanced service binding. The basic service binding is established in an Ethernet DSLAM between a VLAN within the Access Domain and an Asynchronous Transfer Mode (ATM) Permanent Virtual Circuit (PVC) on the local DSL loop. The advanced service binding is created in a Broadband Remote Access Server (BRAS) between the IP client and the service. The basic service binding may also be combined with the BRAS-based advanced service binding.
FIG. 1 is a simplified block diagram illustrating a basic service binding. The IEEE has developed a standard for Ethernet access control, IEEE802.1x. Originally this standard was intended for switched Ethernet networks, but during the standardization process it was adapted to be used for wireless LANs (IEEE802.11). However, the basic principles are still considered applicable for controlling access to switched Ethernet. IEEE802.1x is an integrated part of the Windows XP operating system. Future versions of other operating systems may also include the feature, making this a commonly accepted login interface.
A basic service binding is created by assigning an IEEE802.1Q VLAN ID of a Service VLAN (S-VLAN) 11a, 11b to a subscriber line PVC 12a, 12b. An IEEE802.1p priority value is also associated with this binding, and is used to ensure Quality of Service (QoS) within the Access Domain 13. The Ethernet DSLAM 14 tags upstream traffic, from the Customer Premises Equipment (CPE)/Network Terminal (NT) 15 to the S-VLAN, with the assigned VLAN ID and priority value before forwarding the traffic upstream. Downstream Ethernet traffic, from the S-VLAN to the CPE/NT is mapped by the Ethernet DSLAM to the correct PVC by inspecting the VLAN ID, 802.1p priority, and destination MAC address. Each subscriber line may have multiple PVCs corresponding to different services.
FIG. 2 is a simplified block diagram illustrating an advanced service binding. Services 16, 17 connect through a BRAS 18 to an access domain 19 and the Ethernet DSLAM 14, which connects through a local loop 21 to the CPE/NT 15. The service bindings made in a BRAS are often based on the Point-to-Point Protocol (PPP) as the access protocol. With this protocol, a session is initiated from the end-user device (CPE/NT) towards the BRAS. During this session establishment, the service binding is created, typically based on the login credentials supplied by the end-user's CPE/NT.
FIG. 3 is a simplified block diagram illustrating a basic service binding combined with the BRAS-based advanced service binding. The basic service binding portion is again created by assigning an IEEE802.1Q VLAN ID of an S-VLAN 11a, 11b to a subscriber line PVC 12a, 12b. An IEEE802.1p priority value is also associated with this binding, and is used to ensure QoS within the access domain 13. The Ethernet DSLAM 14 tags upstream traffic, from the CPE/NT 15 to the S-VLAN, with the assigned VLAN ID and priority value before forwarding the traffic upstream. Downstream Ethernet traffic from the S-VLAN to the CPE/NT is mapped by the Ethernet DSLAM to the correct PVC by inspecting the VLAN ID, 802.1p priority, and destination MAC address. Each subscriber line may have multiple PVCs corresponding to different services. The advanced service binding portion includes BRASs 18a, 18b which connect respective S-VLANs 11a, 11b to services 22-25.